Fabrication of GaN-based Schottky barrier diodes on AlN templates and their application to hydrogen gas sensors

Abstract

Pt Schottky diodes were fabricated on high-crystal-quality Al0.2Ga0.8N/GaN epitaxial films grown using epitaxial AlN/sapphire template (AlN template). It was confirmed that reverse leakage currents in Schottky diodes formed on AlN template were drastically reduced compared with samples on sapphire formed with a conventional low-temperature buffer layer. Hydrogen-sensing characteristics were also investigated for a Pt/AlGaN/GaN Schottky diode formed on AlN template. The diode sensor exhibited sufficient changes in the reverse current even under exposure to extremely slight H2 concentration of 50 ppm and exhibited clear reversible responses.